For the use of a Registered Medical Practitioner or a Hospital or a Institution only.

ANTISPASMODIC, ANTICHOLINERGIC AGENT

For the relief of symptoms associated with voiding, such as frequent urination, urgency, urge incontinence, nocturia, and incontinence in patients with uninhibited neurogenic bladder contractions and in those patients with reflex neurogenic bladder

ACTIONS :
Oxybutynin chloride is a tertiary amine anticholinergic agent which exerts an antimuscarinic as well as a direct antispasmodic action on smooth muscle. Oxybutynin chloride also possesses useful analgesic and local anaesthetic properties. Oxybutynin possesses one fifth of the anticholinergic activity of atropine, but has four to ten times the antispasmodic activity when tested on rabbit detrusor muscle. Oxybutynin chloride has no effect at skeletal neuromuscular junctions or autonomic ganglia. In patients with uninhibited neurogenic and reflex neurogenic bladder conditions, cystometric studies have demonstrated that oxybutynin chloride increases bladder capacity, diminishes the frequency of uninhibited contractions of the detrusor muscle and delays the initial desire to void. Oxybutynin chloride thus decreases urgency and the frequency of both incontinent episodes and voluntary urination. These effects are more consistently improved in patients with uninhibited neurogenic bladder. The onset of action is approximately one hour after an oral dose and its duration is 6-10 hours.

PHARMACOKINETICS :
Oxybutynin chloride is rapidly absorbed from all parts of the gastrointestinal tract except the stomach, and peak plasma levels are attained within one hour of oral administration. The absolute bioavailability of orally administered oxybutynin chloride is about 6 %. Oxybutynin distributes readily in the body compartments and there is no evidence of accumulation from multiple dosing. Oxybutynin chloride undergoes significant first pass metabolism. Very little unchanged medicine or metabolites are detected in the urine suggesting the importance of biliary excretion. Glucuronide conjugation, de-ethylation, ester hydrolysis, and hydroxylation at the 3’ and 4’ sites on the cyclohexyl ring have been identified as possible metabolic pathways with phenylcyclohexylglycolic acid and N-desethyl-oxybutynin being the two known metabolites in man. Phenylcyclohexylglycolic acid is pharmacologically inactive and is the major metabolite while N-desethyl-oxybutynin has similar pharmacological activity to oxybutynin chloride. Desethyloxybutynin and oxybutynin N-oxide are the metabolites found in rats. No metabolite activity is known for either of these metabolites and oxybutynin N-oxide is unstable. Oxybutynin N-oxide does not appear to be present in man. Oxybutynin chloride does not appear to have enzyme-inducing properties. Oxybutynin is eliminated from the plasma with a half-life of less than 2 hours. Studies have shown oxybutynin chloride to be rapidly absorbed in the elderly with maximal plasma levels being reached in less than one hour. Plasma levels then decreased biexponentially with an elimination half-life of about 2.5 hours. After repeated administration there was a tendency towards an increase in AUC and elimination half-life. Because it is primarily metabolised in the liver its use in hepatic impairment should be carefully monitored.

INDICATIONS :
OXYBUTYNIN CHLORIDE TABLETS is indicated for the relief of symptoms associated with voiding, such as frequent urination, urgency, urge incontinence, nocturia, and incontinence in patients with uninhibited neurogenic bladder contractions and in those patients with reflex neurogenic bladder.

DOSAGE AND ADMINISTRATION:

Administration :
OXYBUTYNIN CHLORIDE TABLETS is administered orally.

Dosage :
OXYBUTYNIN CHLORIDE TABLETS is not recommended for children under 5 years. Pre-treatment examination should include cystometry and other appropriate diagnostic procedures. Cystometry should be repeated at appropriate intervals to evaluate response to therapy. Appropriate antimicrobial therapy should be instituted in the presence of infection.

Adults :
The usual dosage is 5 mg taken 2 to 3 times daily. The maximum recommended dose is 5 mg taken 4 times daily.

Elderly patients :
Initially treatment should be 2.5 mg taken 2 times daily, and increased as necessary.

Children over 5 years :
The usual dosage is 5 mg taken twice daily. The maximum recommended dose is 5 mg taken 3 times daily.

CONTRAINDICATIONS :
OXYBUTYNIN CHLORIDE TABLETS is contraindicated in patients with urinary retention, gastric retention, myasthenia gravis and other severe decreased gastrointestinal motility conditions, uncontrolled narrow-angle glaucoma and in patients who are at risk for these conditions. OXYBUTYNIN CHLORIDE TABLETS is also contraindicated in patients who have demonstrated hypersensitivity to the drug substance or other components of the product. OXYBUTYNIN CHLORIDE TABLETS contains lactose which is contraindicated in patients with galactosaemia, the glucose-galactose malabsorption syndrome, or lactase deficiency.

WARNINGS AND PRECAUTIONS :
Diarrhoea may be an early symptom of incomplete intestinal obstruction especially in patients with ileostomy or colostomy, and in this instance treatment with OXYBUTYNIN CHLORIDE TABLETS would be inappropriate and possibly harmful.
OXYBUTYNIN CHLORIDE TABLETS should be cautiously prescribed to patients presenting ulcerative colitis, since intestinal motility may be suppressed to the point of producing a paralytic ileus and promote or aggravate toxic megacolon - a serious complication.
OXYBUTYNIN CHLORIDE TABLETS should be used with caution in the elderly and in patients with autonomic neuropathy, hepatic or renal disease.
OXYBUTYNIN CHLORIDE TABLETS should not be taken by patients exposed to high environmental temperatures, since heat stroke and fever may result from decreased sweating.
OXYBUTYNIN CHLORIDE TABLETS should be cautiously prescribed to patients presenting hiatus hernia associated with reflux oesphagitis, since this condition may be aggravated by anticholinergic medicines.
OXYBUTYNIN CHLORIDE TABLETS may invoke photosensitivity in some individuals.
OXYBUTYNIN CHLORIDE TABLETS may aggravate the symptoms of hyperthyroidism, coronary heart disease, congestive heart failure, cardiac arrhythmias, tachycardia, hypertension, and prostatic hypertrophy.
OXYBUTYNIN CHLORIDE TABLETS may produce drowsiness and blurred vision. Patients should be cautioned that engagement in potentially hazardous activities requiring mental alertness such as operating machinery or driving a motor vehicle may be inappropriate while taking this medicine.

PREGNANCY AND LACTATION:

Pregnancy : Category B1
Oxybutynin chloride should not be prescribed to pregnant patients or patients planning pregnancy unless in the opinion of the medical practitioner, the probable benefits outweigh the potential risks to the foetus.

Nursing mothers :
It is not known whether this drug is excreted in human milk. Because many drugs are excreted in human milk, caution should be exercised when oxybutynin chloride is administered to a nursing woman.

Paediatric Use :
The safety and efficacy of oxybutynin chloride administration have been demonstrated for paediatric patients 5 years of age and older.

Geriatric Use :
Clinical studies of oxybutynin chloride did not include sufficient numbers of subjects age 65 and over to determine whether they respond differently from younger patients. Other reported clinical experience has not identified differences in responses between healthy elderly and younger patients; however, a lower initial starting dose of 2.5 mg given 2 or 3 times a day has been recommended for the frail elderly due to a prolongation of the elimination half-life from 2–3 hours to 5 hours. In general, dose selection for an elderly patient should be cautious, usually starting at the low end of the dosing range, reflecting the greater frequency of decreased hepatic, renal, or cardiac function, and of concomitant disease or other drug therapy.

INTERACTIONS AND INCOMPATIBILITIES :
The concomitant use of oxybutynin with other anticholinergic drugs or with other agents (e.g., atropine, hyoscine, ipratropium bromide, propantheline bromide, benzhexol hydrochloride, dicyclomine hydrochloride.) which produce dry mouth, constipation, somnolence (drowsiness), and/or other anticholinergic-like effects may increase the frequency and/or severity of such effects. Anticholinergic agents may potentially alter the absorption of some concomitantly administered drugs due to anticholinergic effects on gastrointestinal motility. This may be of concern for drugs with a narrow therapeutic index. Mean oxybutynin chloride plasma concentrations were approximately 3–4 fold higher when OXYBUTYNIN CHLORIDE TABLETS was administered with ketoconazole, a potent CYP3A4 inhibitor.

Other inhibitors of the cytochrome P450 3A4 enzyme system, such as antimycotic agents (e.g., itraconazole and miconazole) or macrolide antibiotics (e.g., erythromycin and clarithromycin), may alter oxybutynin mean pharmacokinetic parameters (i.e., Cmax and AUC). The clinical relevance of such potential interactions is not known. Caution should be used when such drugs are co-administered. OXYBUTYNIN CHLORIDE TABLETS may also enhance the effects of alcohol.

INFORMATION FOR PATIENTS :
Patients should be informed that heat prostration (fever and heat stroke due to decreased sweating) can occur when anticholinergics such as oxybutynin chloride are administered in the presence of high environmental temperature. Because anticholinergic agents such as oxybutynin may produce drowsiness (somnolence), or blurred vision, patients should be advised to exercise caution. Patients should be informed that alcohol may enhance the drowsiness caused by anticholinergic agents such as oxybutynin.

TREATMENT OF OVERDOSAGE :
Overdosage should be immediately treated by gastric lavage, and intravenous administration of physostigmine 0.5 to 2 mg repeated as necessary but not exceeding 5 mg. Fever responds to symptomatic treatment e.g. alcohol sponging and ice packs. Excitement may be treated with sodium thiopentol 2 % solution given slowly intravenously or chloral hydrate 100-200 ml of a 2 % solution by rectal infusion. Tachycardia may be treated with propranolol and urinary retention with catherisation. Paralysis of the respiratory muscles may require artificial respiration.

STORAGE :
Store below 30°C, protected from moisture and light.
Do not refrigerate.

Disclaimer : For the use of a Registered Medical Practitioner or a Hospital or a Institution only. Also it is not intended to be used by healthcare professionals or patients for the purpose of prescribing or administering these products. Questions regarding the complete and current content of product labeling / specification / presentation should be directed to SGPharma.